(Bug 4903) Check whether we have a .full element properly

find(".full") returns an empty array [] when there's no full elements.
Which means that we falsely assume that this comment has been expanded
and mark it as such. Which then breaks nested expansion. Tsk.
Merge pull request #284 from afuna/fix-nested-expands-bug4903

(Bug 4903) Check whether we have a .full element properly